1. Field of the Invention
This invention concerns a liquid jet recording head for use in a liquid jet recording apparatus, together with a manufacturing method therefor, and a liquid jet recording head drive circuit and drive method.
A liquid jet recording apparatus comprises one or more nozzles, a liquid jet recording head having a liquid chamber in contact with those nozzles, and a liquid supply system. By imparting energy to the liquid with which the liquid chamber is filled, that liquid is jetted from the nozzles, by which means text characters or graphical data are recorded. Means for imparting the energy to the liquid in general use include means for pressurizing the liquid inside the liquid chamber using a piezoelectric device, and means for heating the liquid inside the liquid chamber using a heater. The present invention concerns a liquid jet recording head, and manufacturing method therefor, that comprises means for pressurizing the liquid inside the liquid chamber using a piezoelectric device.
A liquid jet recording apparatus that uses a liquid jet recording head that uses a piezoelectric device comprises a drive circuit for generating a piezoelectric pulsing waveform for driving the piezoelectric device. The present invention concerns a liquid jet recording head drive circuit and drive method wherein a thin film transistor (hereinafter "TFT"), but more particularly a thin film transistor wherein polycrystalline silicon is used in the channels thereof (hereinafter "poly-Si TFT"), is employed.
2. Description of the Related Art
In terms of the prior art for the configuring elements pertaining to the present invention, there is Unexamined Patent Application H5-822140 [1993]. In the patent cited in this example of prior art, a liquid jet recording head and manufacturing method therefor are disclosed wherewith a liquid chamber, liquid flow path, and liquid storage chamber are formed in a monocrystalline silicon substrate, above the liquid chamber in which are formed a vibration plate and piezoelectric device that uses a piezoelectric film. With the liquid jet recording head in the prior art example cited above, however, there are problems, as described below. In the example cited, the configuration is one wherein the liquid chamber and liquid storage chamber, positioned horizontally, are connected via a liquid flow path. That being so, the liquid jet recording head in the prior art cited becomes large in its planar extent. Also, in the prior art cited, the configuration of the part that inputs drive signals to the piezoelectric device is not disclosed, but the configuration is ordinarily one wherein mounting tape having wiring patterns made thereon is connected to connecting terminals provided as electrode leads in the ends or edges of the liquid jet recording head, and a semiconductor integrated circuit wherein is formed a drive circuit made with MOS transistors is connected to the mounting tape. Accordingly, a conventional liquid jet recording head takes up a large space not only in its planar extent but also three-dimensionally. Furthermore, because the drive circuit used is based on semiconductor integrated circuitry, when the number of nozzles is increased, and particularly when a line liquid jet recording head is formed having 100 or more nozzles, the amount of space required is exceedingly large. In order to keep the price of such a drive circuit low, one may configure the drive circuit using a TFT, particularly a poly-Si TFT. However, the drive voltage cannot be raised very high due to concerns about TFT reliability, and the ON resistance of the TFT is larger than in a MOS transistor, wherefore the time required for the voltage waveform to rise in order to drive the piezoelectric device becomes long, leading to a deterioration in the liquid jetting characteristics of the liquid jet recording head.